Most current passenger aircraft window systems comprise multiple panes of acrylic that are coupled together in a multi-piece sheet metal attachment structure. Typically, this structure is installed from the interior of the aircraft and is not maintenance friendly since the passenger seats and aircraft interior wall fascia panels must be removed for access to the window system. Often, the window systems require a deep envelope in the fuselage to accommodate the bulky sheet metal structure holding the multi-pane window.
Many next generation aircraft incorporate transparent structural panels fastened around apertures in the fuselage skin to allow occupants of the aircraft to look through the transparent panels. The panels are typically attached directly to the inside of the fuselage skin. These panels often require external fairing panes to fill in the gap between the inside surface of the skin and the outside surface of the skin in order to provide an aerodynamically smooth surface on the outside surface of the fuselage. The external fairing panes may provide for noise abatement, a thermal barrier, and an abrasion resistant barrier for the internally mounted transparent panel.
The fairing pane attachment system for these next generation aircraft typically must fit inside an envelope equal to the thickness of the fuselage skin, and be capable of allowing installation of the fairing pane from the outside surface of the aircraft fuselage for quick replacement and easy maintenance. Conventional solutions for attaching the outer protective fairing pane have typically been to utilize a picture frame to encase the fairing pane, and fasteners for attachment to the aircraft structure. However, utilizing a picture frame, which generally comprises a raised step around the fairing pane aperture, may not supply a smooth aerodynamic surface on the exterior surface of the fuselage, and may induce drag and reduce performance. Moreover, attachment of fasteners is usually required. Installation of fasteners may be time consuming, may require torque specifications for proper attachment, and may require a maintenance person to remove gloves in order to perform necessary maintenance. Additionally, fasteners may be dropped during maintenance and may cause foreign object damage (FOD) to aircraft systems.
A window assembly and method for its installation is required which will allow for efficient installation of fairing panes from the outside of the aircraft fuselage in a space-challenged envelope. This window assembly may also be utilized in non-aircraft applications.